Search Documents

By R. Hogg, T. F. Dumm

"Abstract - With increasing interest in the physical cleaning of fine coal, there is a need for extension of the sink float analysis procedure to finer sizes. Problems arise, however, in ensuring complete dispersion of the particles in the heavy liquids. A procedure has been developed in which surfactants are used as dispersing agents, and solids concentration is minimized (using a simple formula to estimate the minimum weight needed for statistical reliability). Using centrifuges to increase separation rates and subsieve particle size analysis of the specific gravity fractions, a complete size specific gravity distribution can be obtained. Analyses have been performed on coal samples as fine as -10 µm.IntroductionTraditional gravity separation techniques such as jigging, heavy media and water-only cyclones, shaking tables, etc., have been used to remove impurities from coal ranging in size from about 15.cm (6 ln.) to about 150 µm (100 mesh). The coal washabilty or float-and sink technique ls a well-established procedure for determining the optimum extent to which a coal can be cleaned by such physical separation methods. Because of the desire to recover even finer coal fractions by gravity separation techniques, there is a need to extend the coal washabillty analysis into the ultrafine range. The purpose of this paper ls to describe some of the significant factors that influence fine particle specific gravity separation. Washability analyses have been performed on three ultrafine ( <10 µm) coal samples representing three general mining districts in Pennsylvania. Results of these analyses indicate that the washabillty technique can be successfully applied to ultrafine particles when proper care ls taken."

Jan 1, 1988

By T. F. Dumm

With increasing interest in the physical cleaning of fine coal, there is a need for extension of the sink-float analysis procedure to finer sizes. Problems arise, however, in ensuring complete dispersion of the particles in the heavy liquids. A procedure has been developed in which surfactants are used as dispersing agents and solids concentration is minimized (using a simple formula to estimate the minimum weight needed for statistical reliability). Using centrifuges to increase separation rates and sub-sieve particle size analysis of the specific gravity fractions, a complete size-specific gravity distribution can be obtained. Analyses have been performed on coal samples as fine as -10 µm.

Jan 1, 1987

OFFICIAL Washington is gravely concerned over the adverse military situation caused by the all-out intervention of the Chinese Communists in Korea. What the policies of the United Nations and the United States will be in the new crisis is unknown. However, Stuart Symington, chairman of the NSRB, set the general pattern for mobilization in the near future when he said that this country would move from a "light gray to a dark gray mobilization." The implications of accelerated mobilization for the mining industry are particularly apparent with respect to the manpower situation. Revised policies recently initiated for the recall of reservists may be abrogated, in which case key personnel in the mining industry may face calls to active duty with insufficient consideration given to their indispensability to national defense in their present positions.

Jan 1, 1951

Jan 1, 1882

By Charles Macdonald

It may seem to be almost unnecessary to occupy the time of the Institute in further consideration of a question which has been so comprehensively treated in papers already on file in our own Transactions and in those of the American Society of Civil Engineers. Unfortunately, however, the results of these concerted efforts have not been materially to increase our stock of Knowledge in the direction sought for; and as the necessity for this information is becoming.more and more apparent as the demand for structural materials increases, it is believed that by continuing the agitation by means of discussions in this and kindred societies, whose members are vitally interested in obtaining reliable data as to the properties of the materials they are called upon to work with, public opinion may be educated up to the importance of exerting such an influence upon the law-makers of the country as will result in the formation of a competent board, with adequate means at its disposal, to carry out this great work in a manner alike acceptable to the makers and users of the materials in question. It may be proper in the first place to glance briefly at what has been attempted thus hr, then to indicate some of the more important lines of needed investigation, and finally to consider reasons why government aid may with propriety be sought for in carrying on the work. At a convention of the Society of Civil Engineers held at Chicago June 5th, 1872, it was, on motion of General William Sooy Smith, resolved, that, " Whereas, American engineers are now mainly dependent upon formula for the calculation of strength of the different form of iron and steel, not based on experiments upon American materials and manufacture; and " Whereas, There differ greatly in many of their ch~racteristics front thoae of foreign production, both in their nature and forma: therefore,

Jan 1, 1882

By John C. Smock

The question of the proper valuation of mines of iron ore was suggested to me by the difficulties experienced in getting answers for the United States Census Office, while I was engaged in the work of collecting the statistics of mines in New Jersey and New York. The answers to the questions relating to values of real estate of mine properties varied so greatly that it was necessary to revise them according to some general principles of valuation. Generally the returns of mine proprietors seemed to be too low. There were, however, examples of what would be termed excessive valuation. The subject appeared to be of practical importance, and led to the paper here presented. The following table of selected mine statistics is given, prefacing the discussion of the principles of valuation. It is in part made up of census returns and partly of data obtained directly from mine owners and managers. The mines which were selected for the several groups and mining districts include nearly all of those from which the more full and carefully filled returns were received, and are also representative of their respective districts. Hence the averages obtained from them become good types of these groups or districts. The mines of New Jersey appear in six groups, each containing from three to eleven mines, or, in all, thirty-four mines. The magnetic iron ores of New York are in four well-marked groups, and there are twenty-six mines in them. Then follow the red hematite mines of St. Lawrence and Jefferson counties; and, lastly, the brown hematite groups of Dutchess and Columbia counties, and those of the adjacent parts of Connecticut and Massachusetts. The whole number of mines represented by the table is eighty-eight, of which twenty-eight are hematite mines. The first column gives the value of the real estate; the second that of the plant; the third is the sum of these two, or the capital invested. Then follow the number of men employed, the amount of wages paid during the census year, and the value of materials used in mining and preparing the ores for market." The seventh column gives the total expendi-

Jan 1, 1882

By Thomas R. Kuesel

Just south of the L&apos;Enfant Station in Seventh Street, the WMATA system splits into two branches, each comprising twin single-track soft ground tunnels. Immediately at the beginning of the section, Interstate Route 95 crosses transversely over the alignment in open cut, removing most of the cover over the tunnels. Seventh Street spans I-95 on a bridge whose abutments and pier also cross transversely over the four tunnels, with their footings as little as 7 feet above the tunnel crown (Figure 1). Soil investigations revealed that the tunnels would have to be driven through mixed face, with a clay invert and a waterlogged sand crown. Thus, there was a good chance that the roof would fall in, leaving 1-95 and the Seventh Street Bridge in a crater. Since there was no roof that could be counted on, these were figuratively (and potentially truly) Washington Metro&apos;s Topless Tunnels (Figures 2 and 3). DESIGN ALTERNATIVES Faced with this situation, the designers considered several options, including temporary detours that would permit demolition of the bridge and building tunnels under the 1-95 Freeway by cut-and-cover methods. They also investigated structural underpinning of the bridge and freeway pavement, and strengthening the bridge abutments and center pier by post-tensioning to enable them to span over any subsidence trough.

Jan 1, 1976

By William S. Alldredge

The Washington Metropolitan Area Transit Authority(WMATA) officially came into existence in February 1967 after the District of Columbia, Maryland, and Virginia joined in a com¬pact pursuant to Federal creative legislation signed the previous November to build a regional rapid rail transit system called METRO (1). The parent organization was the National Capital Transportation Agency (NCTA), a Federal agency, subject to Federal statutes and regulations. Soon after the completion of the transition from NCTA to the new "non-Federal" status of the Authority, the Board of Directors of the Authority formally adopted procurement policies and procedures (2). These are specific statements concerning competition by formal advertising for bids or by solicitation of proposals for negotiation, contracting authority, approval of awards, awards of contract modifications, and processing of claims and disputes. These policies and procedures are silent as to Federal procurement statutes and regulations. But because of the Authority&apos;s origin, the sensitive nature of the compact among the several sovereign jurisdictions, Federal financing of two-thirds of the costs, and the resultant surveillance by the General Accounting Office over staff operations, the Authority&apos;s procurement practices follow closely Federal regulations adapted to WMATA&apos;s needs. This is an important point and is the foundation of contractual relations between the Authority as the owner and its construction contractors. Various constraints and flexibilities of this arrangement with respect to excavation and tunneling contracts will be pointed out in the ensuing discussions.

Jan 1, 1974

By Oberlin Smith

The experiments described in this paper are very incomplete and only preliminary to those I hope to make in the future. Having had a good deal of experience in cutting, forming and drawing sheet-metals, and feeling a great interest in the commercially new and wonderful metal, aluminum, I applied to my friend, Mr. A. E. Hunt, for some specimens in sheet-form, that I might, from time to time, test its working-properties in presses with which we happened to be experimenting at the works of the Ferracute Machine Company. The chances for such trials being accidental only, and the time having been limited to the last few weeks, no crucial experiments have been tried, and no exact data have been obtained for a rigid comparison with other metals. The results of what little we have done, however, are shown in the articles exhibited in connection with the reading of this paper, which comprise various cups, plates, boxes, bells and cartridge-cup and shells. For the latter I am indebted to my friend, Mr. Hobbs, of the Union Metallic Cartridge Co., who, at my request, ran several pieces of sheet-aluminum through the dies with which he was making brass cartridges. The specimens are rougher than they would be had the metal not been a little too thin for the particular dies which he happened to be running.

Jan 1, 1890

By Richard Pearce

IN looking around me for some subject on which to frame an address for this meeting, it has occurred to me that some results of observation and investigation, in regard to the varied conditions under which gold is found, may possibly prove of interest. The subject is one which frequently crops up in discussions at our meetings, but there is always an immense amount of uncertainty expressed as to the actual condition in which the gold exists in any particular ore. It follows, therefore, that any light which might be shed on this rather complex subject, would be of value to science and of service to mining and metallurgical practice. In some investigations which I have, from time to time, been led to make, for the purpose of determining to what extent an ore might be concentrated, I have been astonished at the very varied and apparently inexplicable results encountered, and have been naturally led to inquire into the causes for such seeming inconsistency. The mines of Gilpin county, Colorado, where gold was first discovered in that State, furnish an infinite variety of examples of its occurrence, and it was here that difficulties first presented themselves to the Colorado miners, in the sudden transition from what is called " free-milling gold-ore " to an ore characterized by properties which make the ordinary treatment by amalgamation stamp-mills utterly impracticable. So long as mining was limited to what might be called the zone of oxidation in the veins, just so long might amalgamation be conducted without difficulty; but directly the miner reached a point beyond the influence of the oxidizing power of the surface waters, the gold resisted all attempts at amalgamation, and recourse • was had to smelting.

Jan 1, 1890

By George F. Kunz

Jan 1, 1902

By R. W. Raymond

The sudden death of Dr. Drown, on Nov. 17, 1904, brought to multitudes the pang of personal loss. Of all those who, as students at Lafayette College, the Massachusetts Institute of Technology and Lehigh University, were brought under his influence, not one can have forgotten him, and all will now acknowledge, with an unfading gratitude, what they owe in professional equipment to his wise, clear, skillful guidance, and in character to his sympathetic, stimulating personality. Outside of this wide circle, the experts of both hemispheres will lament the departure of one who, in his department of scientific investigation, both knew what work was needed, arid how to do it so that it needed not to be done again. The older members of the Amierican Institute of Mining Engineers will remember with gratitude the part he took, as Secretary from 1873 to 1884, in promoting the interest of that organization, and in shaping the plan and policy which it has followed with such noteworthy success. And, in addition to all these (though partly included among them), there are a host of friends, who can scarcely think of the public loss by reason of their own. Thomas Messenger Drown was born March 19,1842, at Philadelphia, Pa. His parents were natives of New England; and he was the youngest of their three sons. He received his preliminary education in the public schools and the High School of Philadelphia, from which he was graduated in 1859. Be-

Jan 1, 1906

By John A. Church

In the year 1874, when the price of pig-iron was still high, that staple product became the subject of discussion in the newspapers and among those philosophers who are determined to know the "reason why" for all things. The object of the inquiry was to find out Why iron did not fall in price as much as some other things had fallen. Indeed, there seemed to be an impression that iron and gold ought to move on nearly parallel lines, for the fact was constantly brought forward that iron then cost twice as much as it did before the war, though gold had returned to within twelve or fifteen per cent. of its former value. After some time the papers, by what seemed to be nearly unanimous consent, reached the conclusion that the maintenance of high prices was the work of the furnace proprietors, who, as the result of their shrewdness, were pocketing enormous profits. No proof was given to support this opinion, and the figures of cost and sale that were produced were of the most general kind, and used in the most vague manner. Visiting the president of the Thomas Iron Company, whose great works at Hokendaqua and Catasauqua, in Pennsylvania, are so well known as the largest and among the best conducted in America, I found him quite willing to meet the vague suspicions of the newspaper wiseacres, by a publication of the figures contained in the furnace-books of his company. These were accordingly given to the world through the Engineering and Mining Journal, and attracted the general attention they so well deserve. Though my own name became connected with these statistics, from the fact that I used them as the basis for the first attempt ever made to calcalate the furnace economy of an American works, I can, without the suspicion of egotism, say that the statistics referred to are the most valuable contribution the literature of American blast-furnace work has yet received, for their interest is independent of personal considerations, and due entirely to the fact that they represent faithfully the details of practice in one of the most prominent American works. They are an exact transcript of the furnace-books, and form a body of accurate information of the greatest value to the metullurgical student. Their importance is shown by the fact that though the theoretical conclusions which I based upon them have been several times attacked, not one of my critics has made the slightest contribution to

By T. Egleston

At the Dover meeting of the Institute, Mr. F. A. Canfield showed some of the members a machine which he had invented for dressing mineralogical and geological specimens, which he has since modified and brought to such a high state of perfection, that after having used it for several months in preparing specimens for the cabinet of the

By H. M. Chance

Probably no other prosperous mining district is so little known as the Black Hills. The name leads one to assume that the district is a rolling country, consisting of more or less insignificant hills. Nothing could be more untrue, as the Black Hills is an elevated region rising to heights of 7000 and 8000 feet above sea-level, and broken by deep gorges and ravines. It is, in fact, a mountainous country in all that that term implies ; but the cañons and gorges are of such a character that the country is easily penetrated by railroad-lines, and good wdgon-roads exist to-day, affording access to every portion of it. Aside from the stampede to the Black Hills country in 1876, when gold-placers were discovered, and 15,000 or 20,000 people became infected with the mining fever, the region has never had a mining " boom." Quartz-mining commenced in 1877 or 1878, and has been successfully prosecuted ever since; the output of gold steadily growing, until at present the yield is about $7,000,000 annually. This great production is about equally divided between two entirely different classes of deposits. The first class, comprising the so-called quartz or free-milling ores (of which the Homestake mine is the principal producer), are veins of generally steep dip, in the older metamorphosed rocks, and similar to the veins worked in other mining districts. The second class of mines is located in what is known as the " siliceous gold-belt." The Siliceous Gold-Belt. This belt, more particularly to be described in this paper, lies in the immediate vicinity of Deadwood and Lead City, and covers an area 6 or 7 miles in length by 3 or 4 miles in width. The formation in which the siliceous ores are found is a nearly horizontal series of sandstones and shales, generally

Jan 1, 1901

By P. H. Dudley

I have taken the liberty of calling the researches herein mentioned industrial, to distinguish them from those strictly scientific, where every known appliance is used to insure accuracy in determining principles. The industrial researches are made to ascertain wherein we have failed to embody, in practice, the principles which have been fully demonstrated by the more purely scientific investigations. So far the researches have been mostly confined to the conditions of combustion as used in locomotive furnaces, although we have examined, to some extent, furnaces under marine and stationary boilers. The products of complete combustion are gases, and, knowing what we should have, it is at once shown by analyzing the products whether the desired reactions are taking place. In spite of imperfect furnaces, lack of system in the arrangement of grate-bars and exhaust nozzles, the results are not altogether vitiated, because the analyses are not closer than one-tenth of one per cent., as under the present conditions it is hardly possible to collect gas exactly under the same conditions at different times. All of &apos;our industrial operations have developed in the past few years so rapidly, nearly all of them paying, that,, until within the past three years, comparatively little attention has been given to their economy outside of the profession. Great corporations have not asked and considered the question in earnest, can we utilize our heat so as to produce the same effect at less cost? The applications of heat are so extensive, entering into every branch of industry, the principal power used to carry on metallurgical processes, to conduct transportation, that its econonlical generation becomes of universal importance; in fact, its economical generation and application is the leading industrial question of the day. It is stated by those who have given the subject much attention, that in our best steam-engines not over 10 per cent of the theoretical value of the fuel is utilized, and upon locomotives it is far less, probably not exceeding under the most favorable circumstances 5 or 6 per cent. In recent experiments made with the dynagraph, in drawing trains upon the Lake Shore and Michigan Southern Railway from Cleveland to Erie, 941/2 miles, we found the force required to draw a stock train of 709 tons to be 2,498,396,320 footpounds, exclusive of the force to move the locomotive itself. We

By Albert H. Chester

During the summer of 1875 I visited some of the iron mines of Houghton County, Mich., and was quite interested to observe the progress made there within a few years. Working in open pits is gradually giving place to underground work in most of the mines where this system is practicable. In some cases, as in the Lake Superior Mine, the body of ore is so irregular, and the deposit so liable at any time to be pinched out, or nearly so, that it. has been found impractical, if not impossible, to lay out any plan for systematic underground work. But in many other mines the deposit is so regular in character, that the work can be laid out in shafts at regular intervals, and a series of 60 feet levels. The Michigammi Mine, opened in 1872, and first worked in 1873, is arranged on this plan, though some quarrying is still done. But the men are being put at overhead stoping as fast as it can be got ready for them, and before long it will all be worked in this way. The New York Mine is undergoing a similar change to the pillar system, and several others have either been changed, or it is about to be done. My principal object in visiting this region was to obtain samples from some of the important mines, so as to be able to answer the question: "What is the average percentage of iron in the Lake Superior ores?" Most iron furnaces work on mixtures of ore, so that it is impossible to tell, from their records, just the percentage in each one.

By Clemens Jones

THE analytical history of phosphorus in its relation to the metallurgy of iron is an interesting study, the progress of which runs parallel with the development of the greatest industry in the world. Without the means of finding out how much phosphorus crude pigiron contained, the Bessemer steel process would have been impossible. To do this was originally tedious and slow work. On the other hand, the " direct" process of to-day, as well as the various special processes for steel or iron, have demanded the utmost rapidity in the operations of analytical chemistry. In general, any rapid process for the conversion of unrefined metal into a product of standard composition depends upon the rapidity of some accurate means employed to control it. Moreover, in our modern practice, it is not improbable that the differences in physical properties among the various makes of iron or steel are affected, if not produced, by the use of different methods of analysis. Recourse is always had for correction to the ((standard methods," but I incline to think that these methods are susceptible to error. It is very certain that the system of duplicates would not be resorted to, if the fact were otherwise. Even when duplicated, under the most careful and skilful manipulation, these standard methods produce disagreements. In proof of statements like these, which may sound. heretical, I hope, further on, to cite some evidence worthy of attention. I do not now mean to lay claim to the distinction of discovering the ultimate corrective. That result will come, no doubt, in. time, as the product of the experience of many workers. In the case of phosphorus, as of the other ingredients of iron or steel, a great deal has been done to accommodate the methods of analysis in rogue to the growing necessity for more rapid procedures: Much of this work has concerned what might be called the incidents of method. There is no better example of the accumulation of these incidental improvements than the work done on phosphorus; and I

Jan 1, 1890

By Robert W. Hunt

No matter how perfectly sectioned or skilfully manufactured the rails used may have been, or with what care the road-bed may he maintained, legitimate results from these important factors cannot be secured unless proper attention is bestowed upon the joint-fastenings. In this country, splice-bars of various patterns furnish the practically universal joint. Other forms have been used, and are now being experimentally tested, but the typical American rail-joint consists of angle-plates or splice-bars. At the same time, it is true that scarcely a railroad engineer is satisfied with his joint. He may consider it the best of which he has knowledge, but at the same time he is well aware of many of its weak points.

Jan 1, 1890

To the American Institute of Mining Engineers: The committee appointed at the February meeting upon Railway Resistances would respectfully report: That one person has been constantly employed in calculating the results of the data taken prior to March 1st, 1876. Also to complete the data taken upon the Lake Shore and Michigan Southern Railway, a diagram was taken upon a through freight train from Cleveland to Chicago, and one from Chicago to Cleveland. So that now we have diagrams from Buffalo to Chicago and return, which, when fully worked up, will give results of the utmost importance in determining the cost of transportation of freight. These data will be of much importance in determining the proper methods of equating grades and curves, which is so essential in the location of new lines. The calculations show that instead of our attempting to formulate results from data obtained on one road, it will be best for the interests of transportation to enlarge the scope of our inquiries, and to extend the experiments so as to include all of the more probable causes which affect the cost of transportation. Were the details of railway equipment constructed alike, much work, which is now necessary, would be saved. It is not uncommon to find upon the same road 10 to 30 different patterns of something in construction to subserve the same purpose, which more or less modifies the friction of the cars. Take the majority of our trunk lines, with this diversity of construction, together with the varying conditions of track and manner of operating, and it will be at once seen that the labor and time to do the work and arrive at correct conclusions will occupy from two to three years. The results already attained in the short time in which they have been carried on, wholly by private enterprise, simply show what may be expected when the aid necessary is given to render them of the highest value to the great industries of the country. That the information may be general and of the greatest importance to our railway interests, the committee deem it advisable to secure, so